12 January - 20 June 2016

Organic milk contains nearly a third less iodine than conventional milk

7 May 2015

Milk consumption provides the largest source of iodine in UK diets and as a key component of hormones produced by the thyroid gland is particularly important during pregnancy for foetal brain development (Zimmermann, 2009).  Whilst the provision of iodised salt has reduced the incidence of mild iodine deficiency in many countries, in the UK widespread interventions have not been enforced (Phillips, 1997).  This has led to a sustained level of mild iodine deficiency in many populations, notably around 44% of children and adults in Europe (Zimmerman & Andersson, 2011).

Researchers at the University of Reading have carried out a study looking at the effect of milk type and processing on the concentration of iodine in organic and conventional winter milk at retail stores.   Two studies of winter milk are reported.  In Study 1, samples of conventionally pasteurized and organically product full fat, semi-skimmed and skimmed milk were purchased from two leading retailers.  Study 2 comprised of five different milk product types (conventional semi-skimmed, organic semi-skimmed, branded organic semi-skimmed, UHT semi-skimmed and conventional whole milk from Channel Island breeds of cow), these were purchases from four leading retailers in each of three consecutive weeks, beginning in the first week of February 2014 giving a total of 60 samples.

Study 1 samples were measured for fat, protein, lactose concentration and iodine whilst Study 2 samples had only iodine concentration measured.

Both studies showed that the concentration of iodine in organic milk was approximately 34% less than that seen in conventional milk.  No effect of fat class was observed but UHT and branded organic milk had lower iodine concentrations than conventional milk.  The results seen agree with conclusions in an earlier study on summer milk, that there would be an increased risk of sub-optimal iodine status if conventional milk was replaced by organic milk particularly in young women in periods of increased iodine demand such as pregnancy and lactation.

share this article
RSSL endeavours to check the veracity of news stories cited in this free e-mail bulletin by referring to the primary source, but cannot be held responsible for inaccuracies in the articles so published. RSSL provides links to other World Wide Web sites as a convenience to users, but cannot be held responsible for the content or availability of these sites. This document may be copied and distributed provided the source is cited as RSSL's Food e-News and the information so distributed is not used for profit.

Previous editions

Load more editions

Make an Enquiry